we know that
commutative property of multiplication:
We can multiply factors in any orders and the product will be remained same
For example:
[tex] 2*3=3*2=6 [/tex]
Similarly , we have
b(7)
we can write it as
[tex] b(7)=(7)b [/tex]
[tex] b(7)=7b [/tex]
so,
commutative axiom allows that...........Answer